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Seed Chalcid Infestation Patterns on Fraser Fir

Seed Chalcid infestation patterns on Fraser fir

Rapid changes in world’s climate, globalization and current trade patterns are affecting forest pests and the damage they cause. These changes directly impact the development, survival, reproductive cycle and dissemination of pest species while also altering plant host susceptibility and changing the behavioral interactions among pests and other species such as natural enemies and parasitoids.

Seed chalcids (Megastigmus spp.) are tiny wasps whose larvae destroy seeds of various plant species by consuming the megagametophyte (or endosperm) and embryo. Losses caused by Megastigmus have been reported in different conifers in the USA and Europe. We discovered insect larvae in immature and mature Fraser fir seeds and have been improving methods for rearing chalcid adults under lab conditions.

Our preliminary observations indicate that chalcid wasps favor certain Fraser fir families for oviposition but more data is required to confirm this hypothesis. Our main goal is to generate basic information about how the chalcid life cycle is correlated with Fraser fir seed physiology, assess clonal variation and learn more about possible natural chalcid parasites that in the long term will help us improve Christmas trees seed orchards and clone banks and to be prepared for changes in pest behaviors, outbreaks and future invasions.

Male M. specularis isolated Fraser fir seeds in our lab. Photo property of Matthew Bertone and the NC State Plant and Disease Clinic
Female M. specularis isolated from Fraser fir seeds in our lab. Photo property of Matthew Bertone and the NC State Plant and Disease Clinic